Background
Representation by age ensures appropriate translation of clinical trial results to practice, but historically, older patients were underrepresented in clinical trial populations. As the general population has aged, it is unknown whether clinical trial enrollment has changed in parallel.

Methods and Results
We studied time trends in enrollment, clinical characteristics, treatment, and outcomes by age among 76,141 NSTE ACS patients enrolled in 11 phase III clinical trials over 17 years (1994-2010). Overall, 19.7% of patients were ≥75 years; this proportion increased from 16% during 1994-1997 to 21% during 1998-2001 and 23.2% during 2002-2005, but declined to 20.2% in 2006-2010. The number of comorbidities increased with successive time periods irrespective of age. There were substantial increases in use of evidence-based medication in-hospital and at discharge regardless of age. While predicted 6-month mortality increased slightly over time, observed 6-month mortality declined significantly in all age strata (1994-1997 vs. 2006-2010: <65 years: 3.0% vs. 1.9%; 65-74 years: 7.5% vs. 3.4%; 75-79 years: 13.0% vs. 6.5%; 80-84 years: 17.6% vs. 8.2%; and ≥85 years: 24.8% vs. 12.6%).
Conclusions
The distribution of enrollment by age in phase III NSTE ACS trials was unchanged over time. Irrespective of age, post-myocardial infarction mortality decreased significantly over time, concurrent with increased evidence-based care and despite increasing comorbidities.